Silverlight, reference

I try to add a part of another test project to my project.
but i still get an error.

I tryed to add a fileupload part to my application.
But gets this error;

Could not load type 'silverlightfileuploadweb.default3

the code i use is:

 <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default3.aspx.cs" Inherits="SilverlightFileUploadWeb.Default3" %>
<%@ Register Assembly="DC.SilverlightFileUpload" Namespace="DC.SilverlightFileUpload" TagPrefix="DC" %>

The error is on the first row.
But the name of the application is not SilverlightFileUploadWeb.

code behind is:

namespace SilverlightFileUploadWeb
{
    public partial class Default3 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
&nbs ...